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It's funny how weird it can be to be able to see the bottom when you are sailing, like in the Bahamas. I can sail in the Mississippi Sound, where the water is really murky, and not be the least bit concerned that I only have a foot or two of water under me.

But, it always kinds of freaks me out a little when I am sailing in the Bahamas and only have two feet and can actually see the bottom going by.

It's funny how weird it can be to be able to see the bottom when you are sailing, like in the Bahamas. I can sail in the Mississippi Sound, where the water is really murky, and not be the least bit concerned that I only have a foot or two of water under me.

Up here on Lake Superior I am quite used to being able to see 20 to 30 feet down. Our water is cold, and crystal clear. We have plenty of deep water, but going into anchorages you can almost always see to the bottom quite easily. I've sailed in more mirky southerly water, and it freaks me out not seeing the bottom.

02-26-2014 05:07 PM

Group9

Re: How much do you use your Chartplotter?

It's funny how weird it can be to be able to see the bottom when you are sailing, like in the Bahamas. I can sail in the Mississippi Sound, where the water is really murky, and not be the least bit concerned that I only have a foot or two of water under me.

But, it always kinds of freaks me out a little when I am sailing in the Bahamas and only have two feet and can actually see the bottom going by.

02-26-2014 02:55 PM

flyingwelshman

Re: How much do you use your Chartplotter?

I use the Garmin GPSMap 541 and it is on all of the time while underway.

I don't rely on it exclusively for my navigation but as part of an integrated navigation network made up of: the chartplotter, depthsounder, paper charts, Ports cruising guide, sailing directions, compass and, most importantly: eyesight.

I usually plan my cruises by reviewing my intended route on paper charts, starting from the smallest scale and working down to the largest. Then I get on my PC using an old version of Offshore Navigator. I explore anchorages, areas of concern and points of interest there. I use Sailing Directions and Ports Guide to review any specific features of the areas.

I do all of this at home - usually over the winter.

I copy coordinates from Offshore Navigator into Garmin Trip and Waypoint Manager and load them onto an SD card that I can load into my chartplotter.

I have many of the Georgian Bay anchorages and ports loaded onto my chartplotter now so that I can easily access them if I need to in a hurry. The chartplotter also has a listing of marinas, fuel docks and points of interest that you can access easily while underway. There are also satellite shots of marinas and so on for reference.

Once underway I usually start my day by reviewing my paper charts. I always have my paper charts in the cockpit for the area in which I am sailing - even my home waters. I use the chartplotter mostly as a speedometer, but also to calculate ETA etc. I will refer to it on long crossings (especially away from land) to make sure I am on course. In my area there are very few times when you are out of sight of land so I am conning most of the time.

You think it's easy to hit something, or get lost in the Bahamas with GPS, chartplotters, and Explorer charts, you should see what it was like back before all that stuff.

Nothing like piloting yourself into one Cay's harbor, and then finding out you are actually in the harbor of the Cay south of that (did that twice on a cruise we did of the Bahamas in 1987).

Well, I did my first sailing in the Bahamas back in the late 70's, when LORAN coverage barely extended to Nassau... Not that it mattered, as the boats I first took over there didn't have LORAN, anyway :-)

The Tropic Isle Sketch Charts were the Explorer Charts of that era, and the YACHTSMAN'S GUIDE was the cruiser's Bible... Both were actually pretty damn good, at the time... Well, as long as the guy with the yellow cottage that formed a critical range with a conspicuous casuarina didn't decide to paint his house a different color...

Certainly, you had to be paying damn close attention to your piloting in places like the Exumas back then, it was very easy to become confused, or not certain of your position... But I swear, I don't think cruisers really got in any more trouble back then, than they are today... Because of that 'uncertainty', most were far more prudent back then, rarely attempting tricky passages in poor light, or knowing they'd have the sun in their face at late in the day...

Now, I see folks are racing around everywhere with little regard for the importance of reading the water, and simply trusting their plotters implicitly, focused on some screen in their cockpit, instead of the water in front of them... Plotters and e/charts sometimes lie, however - whereas the color of the water, with the sun over your shoulder, NEVER does... :-)

For example, the color of this water approaching Binnacle Hill in the Bight of Acklins says: "You've got no more than 6 inches between your keel, and a billiard table-flat sandy bottom..."

One really hasn't properly done the Bahamas, until you've sailed at a speed greater than the water depth, measured in feet...

The problem has nothing to do with a network. My Garmin handheld has no network capability.

I described the problem last year. The embedded chart is wrong. If you buy the Eastern Caribbean Bluechart chip, the chart is right - as long as you're sure you have the right one activated. See this explanation:

Now that I'm home from work, I can explain a little better, with screenshots from HomePort software that uses my Garmin maps (which I did not have when I posted my note last year). My Oregon 400c handheld comes with an embedded chart of North America, which extends down to include BVI and USVI. That chart is SEVERELY INACCURATE in that area. But if you install Garmin's HXUS030R chip into the handheld, that chart is far more accurate. Only problem on this device is that you can't easily tell which chart is activated. The inaccuracy is so severe that I can't believe that Garmin allows it to stay in circulation. It would be better to delete that area from the embedded chart than to allow the inaccuracy to stay. I can't believe that Garmin is willing to accept the liability of having a defective product out there.

Here are some screenshots from Garmin HomePort to demonstrate the error in their charts. First is the chart from HXUS030R. Note the accurate locations of the ActiveCaptain waypoints, and the shore-hugging track from our PowerCat charter boat, right up to the Customs & Immigration dock:

Now here's the same waypoints and track layed over the embedded chart that comes with the Oregon 400c:

Like I mentioned, even NOAA's chart of that area has problems. Here's the same track on #25641:

And here's the same track on NGA #25609. It's much more accurate. I managed to pull it down off the web a few days before NOAA removed it due to copyright issues with NATO allies who did not want their data to be given away:

02-25-2014 06:21 PM

shananchie

Re: How much do you use your Chartplotter?

[QUOTE=TakeFive;1457722]What was the source of the error? Were the NOAA charts incorrect? Or was it just Garmin's (Raymarine's, etc.) translation of the NOAA chart? Or was the GPS fix off by many hundreds of feet (which I've never seen before)?

Most NOAA charts were drawn up long ago -- well before GPS -- and are only sporadically and partially updated.

So there are plenty of errors in them. And Congress has not seen fit to provide the money to do thorough updates. (Or even to dredge the Intracoastal Waterway, for that matter.)

I keep my boat in Boca Ciega Bay in St. Petersburg. The part of the bay I'm in bears no resemblance to the NOAA chart. It's deeper, has fewer shoals and has a 20-foot deep channel that appears nowhere on the chart. And this is in a well-known anchorage just off the Intracoastal.

BoatUs magazine had a story recently about people running aground on the Intracoastal while religiously following the magenta line on chartplotters and charts.

Well, it turns out the magenta line has not been updated since 1935 -- nearly 80 years ago.

02-25-2014 06:18 PM

Group9

Re: How much do you use your Chartplotter?

You think it's easy to hit something, or get lost in the Bahamas with GPS, chartplotters, and Explorer charts, you should see what it was like back before all that stuff.

Nothing like piloting yourself into one Cay's harbor, and then finding out you are actually in the harbor of the Cay south of that (did that twice on a cruise we did of the Bahamas in 1987).

Amazing, how many folks appear to believe all e-charts are created equal... And, as good as the Explorer Charts are, it's spooky how many out there seem to think Monty & Sarah have charted every single coral head throughout the Bahamas with absolute precision... :-)

Yup, the compute power of the plotter that sits between the ears beats any chart plotter.

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